Chemistry atomic models grade 9

Billard ball model

Who made it? Jhon dalton

• proposed that each element is made up of atoms that are in-divisible and have a specific mass

• he suggested that chemical reactions occur when atoms combine in fixed ratios to form compounds.

J.J thomson Raisin bun model/plum pudding

who made it? JJ thomson

• he discorved the electron

• the atom is a uniformly packed sphere of positive matter with negatively charged electrons(like raisins in a bun)

Ruther fords model (nuclear model)

who made it? Ernest Rutherford

• he concluded that atoms consist of mostly empty space with a dense positively charged nucleus at the center and electrons moving arround this nucleus.

bOhrs Model (Planetary)

Who made it? Niles Bohr

• concluded electrons (planets) orbited the nucleus (sun) at fixed energy levels like our solar system

• electrons could jump between these levels but not exist in the space between them.

Uncertainty principle

Who made it? Werner heinseberg

• showed it was impossible to determine both, the exact position and speed of electrons

Quantum mechanic (electron cloud model)

Who made it? Schrodinger, heinsberg, and others

• proposed that electrons do not have a fixed path around the nucleus. the position of the electron can only be described probabilistically

• this model is used today.